The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art or may not form part of the state of the art at the time of filing, are neither expressly or impliedly admitted as prior art or state of the art against the present invention.
Mobile telecommunication systems, such as those based on the 3GPP defined UMTS and Long Term Evolution (LTE) architecture, are able to support more sophisticated services than simple voice and messaging services offered by previous generations of mobile telecommunication systems. For example, with the improved radio interface and enhanced data rates provided by LTE systems, a user is able to enjoy high data rate applications such as video streaming and video conferencing on mobile communications devices that would previously only have been available via a fixed line data connection.
The demand to deploy fourth generation networks is therefore strong and the coverage area of these networks, i.e. geographic locations where access to the networks is possible, is increasing rapidly and expected to continue to increase. However, although the coverage and capacity of fourth generation networks is expected to significantly exceed those of previous generations of communications networks, there are still limitations on network capacity and the geographical areas that can be served by such networks. These limitations may, for example, be particularly relevant in situations in which networks are experiencing high load and high-data rate communications between communications devices, or when communications between communications devices are required but the communications devices may not be within the coverage area of a network. In order to address these limitations, in LTE release-12 the ability for LTE communications devices to perform device-to-device (D2D) communications is introduced. Communication devices that are operated by a user for these purposes may be referred to as user equipment (UE).
D2D communications allow communications devices that are in close proximity to directly communicate with each other, both when within and when outside of a coverage area or when the network fails. This D2D communications ability allows communications devices that are in close proximity to communicate with one another although they may not be within the coverage area of a network. The ability for communications devices to operate both inside and outside of coverage areas makes LTE systems that incorporate D2D capabilities well suited to applications such as public safety communications, for example. Public safety communications require a high degree of robustness whereby devices can continue to communicate with one another in congested networks and when outside a coverage area.
Other types of relatively new protocols, features, arrangements or sets thereof of mobile telecommunications systems include for example relay node technology which can extend the coverage for base station or another node for communicating with terminals, in terms of throughput and/or geographical coverage. Small cells may also be provided wherein a small cell can be controlled by a base station or operate as a base station with a limited coverage (either geographically or in the terminals accepted by the small cell, e.g. only terminals associated with a specific customer/company account may be able to connect to it). As a result, a variety of technologies, some of them alternative and other compatible technologies, can now be used in a mobile telecommunication system.
In parallel, the development of vehicle-related communications has emerged and attracted a growing interest. These communications can sometimes be called vehicle-to-everything (V2X) communications which can refer to any one or combination of the following: vehicle-to-vehicle (V2V) communications, vehicle-to-infrastructure (V2I), vehicle-to-pedestrians (V2P) communications, vehicle-to-home (V2H) communications and any other type of vehicle-to-something communications. They enable a vehicle to communicate with its environment, be it another vehicle, a traffic light, a level (railroad) crossing, infrastructure equipment in the vicinity of a road, a pedestrian, a cyclist, etc. In a typical V2I scenario, V2I communications is used for collision prevention, driver alerting and/or other intersection related activity. In this kind of embodiment, the V2X-enabled terminal has to find out the relevant Road-Side Unit (RSU) to connect to and exchange information with. More generally, this new set of technologies can enable a variety of features such a convoying of vehicles, safety features, environmental friendly car driving and/or management and can also facilitate the operation of driverless/autonomous cars.
Whilst D2D communications techniques can provide an arrangement for communicating between devices, D2D is generally targeting public safety uses, so-called machine type communication (MTC) applications—which tend to be low-throughput and high-latency communications- or conventional terminals. Also, the D2D communications techniques are generally based on existing mobile network communications techniques which have not been built with applications such as V2X in mind. As a result, they are not designed to deal with high speed terminals as can be found in a V2X environment. As a result, the present telecom systems and arrangements, and in particular D2D ones, face a large number of problems to become suitable or more suitable for V2X or V2X-like types of communications, in particular in respect of V2X or V2X-like communications for fast-moving terminals.